The trophic influence of the sympathetic nerve system on the arterial wall was studied in the auricular artery of the rabbit and compared with the same analysis in the rabbit aorta. From the results it can be concluded that the auricular artery has a different metabolic and enzymatic make-up than the rabbit aorta and therefore pathological processes may not have uniform appearance along the whole vascular tree. The experiments with rabbits where their aortas were coarcted, it was demonstrated that the pressure difference leads to changes in the sympathetic response as well as to changes in endothelial permeability. The possibility of the effect to hypoxic stress due to long term stay in high altitude will be evaluated from the point of its effect on the sympathetic response as well as metabolic changes of the aortic wall. This aspect of our study is of prime importance not only from the point of basic biological mechanisms, but also because the conclusions from this study will have direct practical applicability.